phy: Change mii_bus id field to a string

Having the id field be an int was making more complex bus topologies
excessively difficult.  For now, just convert it to a string, and
change all instances of "bus->id = val" to
snprintf(id, MII_BUS_ID_LEN, "%x", val).

Signed-off-by: Andy Fleming <afleming@freescale.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/net/ucc_geth.h b/drivers/net/ucc_geth.h
index 4fb95b3..9f8b758 100644
--- a/drivers/net/ucc_geth.h
+++ b/drivers/net/ucc_geth.h
@@ -1156,7 +1156,7 @@
 	u16 pausePeriod;
 	u16 extensionField;
 	u8 phy_address;
-	u32 mdio_bus;
+	char mdio_bus[MII_BUS_ID_SIZE];
 	u8 weightfactor[NUM_TX_QUEUES];
 	u8 interruptcoalescingmaxvalue[NUM_RX_QUEUES];
 	u8 l2qt[UCC_GETH_VLAN_PRIORITY_MAX];